of detroit



Aug. 27, 1929. T. P. CHASE INTERNAL BRAKE Filed Aug. 6, 192e me/rubio@ t Gg/m' Mouw? Patented Aug. 27, 1929.

UNITED STATES 1,726,509 PATENT OFFICE.

THERON P. CHASE, OF DETROIT, MICHIGAN, ASSIGNOR TO GENERAL MOTORS RE- SEARCH CORPORATION, F DETROIT, MICHIGAN, A CORPORATION OF DELAWARE.

INTERNAL BRAKE.

Application filed August 6, 1926. Serial No. 127,627.

This invention relates to brakes. The brake is intended primarily for vehicles.

An object of the invention is to provide an improved internal expanding brake. An-

other object is to provide a self-centering cam for expanding the brake member.

The invention also contemplates the use of an expedient to support the brake member in adjustable relation to the drum in its released position.

As a further and especially important object, the invention aims to provide a new anchoring device which shall render it possible to accurately and quickly determine the correct position for the anchoring pin.

Other objects and advantages will be apparent from the following description when read together with the accompanying drawing.

In the drawing, Figure 1 is a vertical section through the brake.

Figure 2 is a vertical section taken on line 2 2 of Figure 1. v

Figure 3 is a horizontal section showing the modified form taken on a line correspending with 3--3 of Figure 2.

Figure 4 is a section substantially on line iiof Figure 2.

Referring by reference characters to the drawing7 the numeral 1 represents the axle, in this case the front axle, of themotor vehicle. The steering knuckle is represented by numeral 3 and the wheel by 5. Upon the wheel is a brake drum 7 secured by bolts 9. Rigid with the knuckle is a backing plate 11 which carries the-anchors for the brake shoes and upon which is rotatably mounted the operating shat't for applying the brake.

The brake employs two shoes 13 anchored to the backing plate, the shoes having the usual friction linings 15 for engaging and resisting the rotation of the drum carried by the wheel. For expanding the shoes a cam 17 carried by a shaft 19 m'ay be rotated. To support the adjacent ends of the two shoes springs 21 and 21 are attached at their remote ends to the two shoes and at their adj acent ends to a convenient common anchor. The springs draw the shoes away from the drum when the cam is turned to release the brake.

Inasmuch as it is desirable to secure a low pedal pressure, the anchor pin of each shoe is located at a point quite well inward from the periphery of the drum.

This invention comprises a novel anchoring means which will now be described. In the case of rigid shoe brakes very accurate Workmanship is required in determining the location of the anchor pin in the backing plate, and the location of the anchor pin hole in the shoe with reference to the face of the lining. The drum diameter must be accurate and its concentricity, when mounted on the wheel, must also be accurate. For quickly, easily and accurately adjusting the position of the anchor pin, the following structural arrangement has been devised.

Each shoes has an anchor pin 23 about which it is to rotate in the action of applying the brake. The pin 23 is to be secured to the backing plate. Beneath the shoe is a bar or link 25. This link is clamped to the backing plate at its two ends. At one end the link has a press fit on a reduced part 24: on the anchor pin 23, and a nut 29 on the anchor pin serves to complete the clamping action. At its other end a body tit bolt 27 and a nut 29 complete the clamping of the link. Preferably the link is shouldered at 31 engage the bolt head to facilitate asse1n- It will be seen from Figure 3 that the hole in the backing plate for the anchor pin 23 is enlarged. The link 25 is mounted so that the center line of the two holes is suiliciently ott the line of reaction of the shoe, so that when the two nuts 29 are loosened the shoe can be expanded in the drum, andwill move about bolt 27 until it is seated in the drum. The nuts on the anchor pin and bolt can then be turned up to secure the link in position, after which movements of the shoe produced by the brake actuating members will be about the anchor pin, and will apply the shoe properly to the drum. Furthermore, since the backing plate is not a very rigid member, the use ot the links serves to stili'en the same at that portion where the shoe is anchored As a means for retaining the shoes on the anchor pins 23, I am adding lugs 33 to the shoes. Over these lugs are the hooked ends of the rod or wire 34 of substantially U-shape, the loop of the rod being engaged under a plate 35 held to the backing plate by a bolt 37. This simple attaching means I make use of for the reason that beneath the drum there is unlikely to be suiiicient clearance for a head on the anchor pin or for other fastening means.

For operating the brake shoes there is employed the cam 17. This cam is carriedV by a shaft 19. Instead of journalling the shaft 19 in the backing plate, it is ournalled in a link pivoted to the backing plate by a pivot bolt 47 radially inwardly from the position of the cam. It may also be positioned a little below the radial line through the center of the cam for a reason to be explained below.

rFhe releasing springs 21 and 21 may conveniently be attached at their adjacent ends to the pivot bolt 47. By the provision of the link the cam, in addition to its rotary movement in separating the brake shoes, is given a bodily' movementy about pivot 47. This bodily movement renders it a floating cam and enables it to move bodily toward that shoe the lining of which may have become worn, with the result that the pedal pressure is equally distributed to the two shoes. Moreover as the lower shoe (Figure 2) is the one to receive the greater lwear owing to the direction of wheel rotation, the lowered position of pivot 47 is adopted.

As a preferred means of supporting the shoes away from the drum in the brake releasing position, the form shown by Figure 1 and Figure 2 is used. In this embodiment of the invention there is employed a sleeve 57 rotatably mounted in the backing plate. T o conveniently ournal the sleeve it is provided with a flange 59 in contact with the inner face of the backing plate. Overlying this flange are two fastening plates 61 held by bolts 63, and between the backing plate and the plates 61, the sleeve 57 may be rotated by any convenient means, openings 63" being shown in Figure 1 just outside the backing plate into any one of which openings a pin may be inserted to assist in rotating the sleeve.

lNithin the drum the sleeve 57 is provided with an eccentric to support the upper shoe under the action of spring 21 and the pull of gravity. lVhen the pedal pressure is released the cam rotates to its released position. The spring 21 pulls the upper shoe down upon the adjustable eccentric. rl"he springs 21 and 21 also serve to restore link 45 to its normal position, should it have been rotated therefrom by the centralizing action of the brake application. The downward pull of spring 21 upon the upper shoe 13 is limited by the engagement of this upper shoe with the eccentric, as will be readily understood. For this reason link 45 cannot rotate below its normal position under the action of spring 21 Furthermore, to prevent spring 21 from swinging link 45 upwardly beyond its normal position and pushing the upper shoe up toward or against the drum, the spring 21 is made somewhat stronger than spring 21, so that such an action is impossible.

As a substitute means to restore and retain the link 45 in its centralized position, and to thereby hold the shoes olf the drum when the brake is released, there may be used, in place of the eccentric described, a detent 51 mounted in a recess of the link 45, as shown in Figure 3. The detent is actuated by spring 53 within the recess to engage a notch 55 formed in the backing plate. The engagement takes place when the lever is in its normal, substantially radial position.

It may be found preferable in this modiiication to use a single releasing spring` 22 in place of the double spring 2l, 2 lhis single spring will have its ends anchored to the two shoes. When the pedal pressure is released and the cam rotates to its brake releasing position, the resilient connecting means withdraws the shoes from frictional contact with the drum, and slight vibratory movements of link 45 will quickly cause the action of the spring` detent to locate the notch of the backing plate and restore the lever carried cam to its mid position.

The eccentric described above for determining the released position of the brake shoe is provided with an openingtherethrough to permit its use as a means for journalling the shaft G5 used in connection with the brake applying` means. The shaft G5 rotatably mounted in the sleeve 57 has on its end outside the backing plate an arm 67, and between this arm 67 and the arm 69 on the cam shaft is a link 71. Suitable means not shown are employed for operating the shaft 65.

I claim:

1. Anchoring means for a brake comprising a brake shoe, an anchoring pin for pivotally mountingr said shoe in a fixed plate, a link secured to said anchor pin, a bolt independently connecting said link to said plate, the opening in the fixed plate for the reception of the anchor pin bein.O enlarged to facilitate assembly.

2. ln a brake, a drum, a backing plate, a shoe, a link having a pivotal connection with said backing plate at one point, means to adjustably connect said link with said backing plate at another point, the brake shoe being pivoted to said link at the point of adjustable connection between the link and the backing plate.

3. ln a brake, a drum, a fixed plate, links pivotally mounted on said fixed plate, means to clamp said links to said lixed plate in selected positions of adjustment, and cooperating shoes pivoted to said links.

4. ln a brake, a drum, a fixed plate, a link pivotally mounted on said fixed plate, means removed from said pivot to clamp said link to said fixed plate in selected positions, said clamping means including a pin and a brake shoe rotatable on said pin.

5. In a brake, a drum, a shoe, means associated with said shoe whereby it may swing about independent pivots when being assembled, one oi' which pivots has movable means to secure said movable pivot in position to serve as the pivot anchor of said shoe in the operation of the brake.

6. In a brake, a drum, a plurality of shoes, a fixed pivot bolt for each shoe and a movable pivot pin for each shoe, the shoes being rotatable about both pivot bolts and pins in the act of assembling, means to render immovable pivots whereby, in operation, the shoes swing about pivots which insure conformity with the drum.

7. In a brake, a drum, a shoe, a fixed plate, a pivot bolt fixed in said plate, a pivot pin movable in said plate, means yrotatable on the fixed pivot bolt and rigid with the movable pin, the shoe rotatable on the movable pivot pin.

8. A brake drum, a fixed support, a brake shoe for frictionally engaging said drum, means associated with said iixed support whereby double pivot connection is given said brake shoe in the act of assembling the same, unitary means to rotate said shoe about both pivots and clamping means whereby after assembly the shoe swings about a single pivot.

9. In a brake mechanism, a drum, a fixed plate, a shoe, means connecting said shoe and plate whereby the shoe may have a bodily movement, including means whereby the shoe is given a pivotal movement, means to clamp said means whereby the movement of the shoe may be restricted to a pivotal movement.

10. In a brake, a pair of shoes, pivot pins for said shoes, lugs on said shoes adjacent the pivots, means to hold said shoes on the pivots comprising a U-shaped member fixedly secured and having its ends bent over said luffs.

I1. A brake drum, a shoe, a backing plate, a link, means to secure the said link to the backing plate at two points, one point being adjustable, the shoe being pivoted to said link at the adjustable point.

12. A brake drum, a plurality of shoes, a

backing plate, independent means to assemble each of said shoes relative to said backing plate including a swinging link, means to fix said link against swinging whereby the pivot of said shoe may be accurately determined for proper engagement with the drum.

13. In a brake, a fixed plate, a drum, a shoe positioned to engage the drum, means to anchor said shoe on said plate comprising a member having a pivotal connection with said plate, pivot means between said shoe and said member, said lastnamed pivot means extending through and being movably associated with said plate, and means to secure said shoe pivot in fixed relation to said plate.

14. In a brake, a drum, a fixed plate, a reinforcing member pivotally secured at one end to said plate, means extending through said plate to adjustably secure said reinforcing member to said plate at its other end, a shoe to engage said drum, said shoe pivoted to said reinforcing member adjacent its adjustable connection with the fixed plate.

15. In a brake, a drum, a backing plate, a plurality of shoes, a plurality of members pivoted to each of said shoes and to said backing plate, and means to prevent pivot movement of each of said members about the backing plate.

16. In a brake, a drum, a backing plate, a shoe, a member pivoted to said shoe adjacent an end of said shoe and to said backing plate, the pivot between said shoe and member extending through said backing plate, and means to secure said first-named pivot fixedly to said backing plate.

17. In a brake, a drum, a relatively fixed plate adjacent said drum, a shoe to frictionally engage said drum, means associated with said shoe and backing plate having a fixed pivotal connection with said backing plate about which pivot the shoe with said means is pivotally movable, said means having a movable connection with the backing plate about which the shoe is independently rotatable, and fastening means to secure said means from movement relative to the backing plate.

In testimony whereof I aiiix my signature.

Trianonl P. CHASE. 

